Easy To Use Patents Search & Patent Lawyer Directory

At Patents you can conduct a Patent Search, File a Patent Application, find a Patent Attorney, or search available technology through our Patent Exchange. Patents are available using simple keyword or date criteria. If you are looking to hire a patent attorney, you've come to the right place. Protect your idea and hire a patent lawyer.

A device for axially conveying fluids, wherein the conveyor part thereof
is entirely magnetically borne and the radial bearing thereof is provided
with sufficient rigidity and efficiently dampened, whereby problems
encountered when passing through critical speeds and the disadvantageous
effects of hydrodynamic and mechanical imbalance of the rotor are
avoided. The magnetic bearing is combined with a hydrodynamic bearing.

1. Device for axially conveying fluids, consisting of a tube-shaped hollow
body (1) which conducts the fluid in an essentially axial manner, in
which a magnetically borne conveying part (4) is arranged in axial
alignment with a motor stator (7) located outside of the hollow body (1)
capable of rotating said conveying part, where the one conveying part (4)
having a magnetic bearing has a rotor blading (11), wherein the magnetic
bearing is combined with a hydrodynamic bearing.

2. Device according to claim 1, wherein the bearing of the conveying part
(4) has an actively stabilising magnetic axial bearing, a passive
magnetic radial bearing and a hydrodynamic radial bearing (13).

3. Device according to claims 1 or 2, wherein the hydrodynamic radial
bearing is executed as a hollow-cylindrical, rotation-symmetrical back-up
ring (13) which is joined to the conveying part (4).

4. Device according to one of the claims 1 to 3, wherein at least one
back-up ring (13) is arranged on the conveying part (4).

5. Device according to one of the claims 1 to 4, wherein the back-up rings
(13) are arranged at the beginning of the motor rotor (8) and/or at the
end of the motor rotor (8) or between these positions as stated.

6. Device according to one of the claims 1 to 5, wherein the axial
dimension of the back-up ring (13) corresponds at a maximum to the axial
length of the conveying part (4).

7. Device according to one of the claims 1 to 6, wherein the axial
dimension of the running surface (14) of the back-up ring (13) is smaller
than the internal surface (16) of the back-up ring (13).

8. Device according to one of the claims 1 to 7, wherein the back-up ring
(13) has the same radial dimension as the rotor blading (11).

9. Device according to one of the claims 1 to 8, wherein the back-up ring
(13) and the rotor blading (11) are joined together.

10. Device according to one of the claims 1 to 9, wherein the back-up ring
(13) has such a radial dimension (thickness) that it can be provided with
a radial profile which serves the purpose of conditioning of the inflow
into the rotor blading (11) of the conveying part (4).

11. Device according to one of the claims 1 to 10, wherein a back-up ring
(13) exists with such an axial reach that the blading (11) over its
entire length is radially restricted from the back-up ring (13).

12. Device according to one of the claims 1 to 11, wherein the running
surface (14) of the back-up ring (13), which points against the internal
side of the tube-shaped hollow body (1), has a surface coating with
emergency running properties and which is, moreover, bio-compatible.

13. Device according to one of the claims 1 to 12, wherein the internal
surface (16) of the back-up ring (13) has a profile (15).

14. Device according to one of the claims 1 to 13, wherein the running
surface (14) of the back-up ring (13) has a running line (17).

Description

DESCRIPTION

[0001] The invention relates to a device for axially conveying fluids in
accordance with the generic term of claim 1.

[0002] In particular, less stable multiple-phase fluids which can undergo
irreversible changes caused by an energy input, such as in the case of
emulsions and dispersions, can run into unstable ranges in a
disadvantageous manner when being conveyed in corresponding devices such
as pumps.

[0003] Blood is a particularly sensitive fluid system. This opaque red
body fluid of the vertebrates circulates in a self-enclosed vessel system
where rhythmic contractions of the heart press the blood into various
areas of the organism. In this case, the blood transports the respiratory
gases oxygen and carbon dioxide as well as nutrients, metabolic products
and endogenous active ingredients. The blood vessel system including the
heart is hermetically isolated from the environment so that, in a healthy
organism, the blood does not undergo any changes, except for the material
exchange with the body cells, when it is pumped through the body by way
of the heart.

[0004] It is known that, when blood comes into contact with non-endogenous
materials or as a result of the effect of energy from an external source,
it has a tendency to hemolysis and clot formation. Clot formation can be
fatal for the organism because it can lead to blockage in the extensive
branching profile of the vessel system. Hemolysis describes the condition
where the red blood cells are destroyed within the body beyond the
physiological dimension.

[0005] The causes for hemolysis can be of a mechanical or metabolic
nature. Increased hemolysis causes multiple organ damage and can lead to
a person's death.

[0006] On the other hand it is evident that it is possible in principle,
under certain prerequisites with reference to constructive aspects, to
support the pumping capacity of the heart or even to replace the natural
heart with a synthetic one. However, a continuous operation of implanted
heart supporting systems or synthetic hearts is presently only possible
with certain limitations because the interactive effects of these
artificial products with the blood and the entire organism still always
lead to disadvantageous changes of the blood and the organism.

[0007] In the state of the art, axial blood pumps are known which mainly
consist of a cylindrical tube in which a conveying part, which is
executed as a rotor of an externally located motor stator, rotates. The
rotor which is provided with a so-called blading, conveys the fluid in an
axial direction after it has been made to rotate. The bearing of these
so-called axial pumps represents a major problem. A purely mechanically
bearing is disadvantageous with regard to blood damage and also the
relatively high friction levels. And the magnet bearing variants as
described up to the present have not, in particular, led to any
satisfactory solution for the bearing conditions in axial pumps.

[0008] In the WO 00/64030 a device for the protective conveying of single-
and multiple phase fluids is described whose conveying part is
exclusively magnetically bearing-located. For this purpose, permanent
magnetic bearing elements for the magnet bearing-location as well as
permanent magnetic elements for the functionality as a motor rotor of an
electromotor are preferentially integrated in the conveying part. The use
of a magnet bearing for the conveying facility as described here makes it
possible to waive bearing elements normally arranged in the flow current
of the fluid to be conveyed which lead to dead water zones and
vorticities of the fluid to be conveyed and, subsequently, have a
negative influence on the current flow.

[0009] The magnetic bearing described here accommodates both the axial as
well as the radial forces. The axial location of the conveying part is
actively stabilised whereas the radial bearing of the conveying part is
effected exclusively passive by means of the existing permanent magnets.
However, the conveying facility as described has several disadvantages.

[0010] The passive magnetic radial bearing is characterised by relatively
low rigidity and dampening where, during the pumping action, problems
occur when passing through critical speeds of the rotor and/or the
bearing. Possibly existing hydrodynamic and mechanical imbalance of the
rotor has serious effects on the function of the pump, particularly when
used as a blood-conveying facility.

[0011] The invention is based on the task assignment of presenting a
device for the axial conveying of fluids whose conveying part is
completely magnetically borne and whose radial bearing has sufficient
rigidity and effective dampening so that problems encountered when
passing through critical speeds and the disadvantageous effects of
hydrodynamic and mechanical imbalance of the rotor are avoided.

[0012] The solution for the task assignment is effected with a device for
axially conveying fluids in accordance with the designating part of claim
1.

[0013] Such is the device for axially conveying fluids, consisting of a
tube-shaped hollow body which conducts the fluid in an essentially axial
manner, in which a magnetically borne conveying part is arranged in axial
alignment with a motor stator located outside of the hollow body capable
of rotating said conveying part, where the one conveying part having a
magnetic bearing has rotor blading, wherein the magnetic bearing is
combined with a hydrodynamic bearing.

[0014] Further advantageous embodiments are stated in the Subclaims.

[0015] The bearing of the conveying part has an actively stabilising
magnetic axial bearing, a passive magnetic radial bearing and a
hydrodynamic radial bearing. The hydrodynamic radial bearing is executed
in a further embodiment of the invention as a hollow-cylindrical,
rotation-symmetrical back-up ring which is joined to the conveying part.

[0016] On the conveying part, at least one back-up ring is arranged, where
the back-up rings are arranged at the beginning of the motor rotor and/or
at the end of the motor rotor or between these said positions.

[0017] In a further embodiment of the invention, the axial dimension of
the back-up ring corresponds, at the maximum, to the axial length of the
conveying part, and the axial dimension of the running surface of the
back-up ring is smaller than one internal surface of the back-up ring.

[0018] The back-up ring has the same radial dimension as the rotor blading
and is joined to it.

[0019] Furthermore as an embodiment, the back-up ring has such a radial
dimension (thickness) that it can be provided with a radial profile which
services the purpose of conditioning the inflow into the rotor blading of
the conveying part.

[0020] In a further embodiment, a back-up ring is provided with such an
axial reach that the blading over its entire length is restricted
radially from the back-up ring. The running surface of the back-up ring
which points against internal side of the tube-shaped hollow body, has in
an advantageous manner a surface coating with emergency run
characteristics and this coating is, moreover, bio-compatible.

[0021] The internal surface of the back-up ring has, in one execution, a
profile which can favourably influence the current flow properties.

[0022] The execution of the running surface of the back-up ring as one
running line leads to particularly favourable friction values.

[0023] The major rigidity and dampening of the radial bearing of the
conveying part is achieved in such a way that, in addition to a magnetic
bearing of the conveying part, a hydrodynamic bearing is envisaged. The
hydrodynamic bearing is achieved by at least one hollow-cylindrical,
rotation-symmetrical back-up ring which is solidly joined to the
conveying part. With a suitable execution of the back-up ring, the rotor
receives major tilting rigidity. Advantageously, this effect is obtained
by a particularly large axial reach of the back-up ring or by the
arrangement of at least two back-up rings at one rotor.

[0024] With a large axial reach of the back-up ring and/or extensive or
complete encapsulation of the blading by means of such a back-up ring,
damaging effects of the radial gap occurring at the blade ends are
advantageously avoided.

[0025] The invention is explained in greater detail based on a drawing:

[0026] The Figures show the following:

[0027] FIG. 1: a schematic illustration of an axial section of an axial
blood pump with back-up ring;

[0028] FIG. 2: a schematic illustration of an arrangement of a back-up
ring on the rotor;

[0029] FIG. 3: a schematic illustration of an arrangement of two back-up
rings on the rotor;

[0030] FIG. 4: a schematic illustration of an arrangement of a back-up
ring with profiled internal surface;

[0031] FIG. 5: a schematic illustration of a back-up ring reaching over
the entire rotor, and

[0032] FIG. 6: a schematic illustration of a back-up ring on the rotor
with a running line on the running surface.

[0033] In an exemplary manner, FIG. 1 shows in an axial sectional
illustration the construction of a category-related axial pump with the
bearing, according to the invention, of a conveying part 4. In its main
parts, the axial pump consists of a tube-shaped hollow body 1 and a pump
casing 3 that includes a motor stator 7 and axial stabilisers 6. The pump
casing 3 lies immediately and rotation-symmetrical on the tube-shaped
hollow body 1. In the interior of the tube-shaped hollow body 1, a fluid
inlet guide facility 5 and a fluid outlet guide facility 5' are
envisaged, between which the conveying part 4, which is rotated by the
motor stator 7, is arranged.

[0034] The conveying part 4 has a magnetic bearing where permanent
magnetic bearing elements 9 and 9 are arranged in the motor rotor 8 and
permanent magnetic bearing elements 10 and 10' are arranged in the fluid
inlet- and fluid outlet guide facilities 5 and 5'. On the motor rotor 8
of the conveying part 4, a rotor blading 11 is envisaged which is
combined with a back-up ring. The magnetically bearing-located conveying
part 4 is rotated by way of the motor stator 7 where, by means of the
oppositely located permanent magnetic bearing elements 9, 9' and 10, 10'
in combination with the axial stabilisers 6, the conveying part is kept
in a floating state and the back-up ring provides for an additional
hydrodynamic bearing-location of the rotating conveying part 4.

[0035] FIG. 2 shows in a schematic illustration the motor rotor 8 with the
rotor blading 11 in a cut-open tube-shaped hollow body 1. In accordance
with the invention, the back-up ring here is arranged in the end zone of
the motor stator 8. The fluid to be conveyed is moved between an internal
surface 16 of the back-up ring 13 and the motor rotor 8. A running
surface 14 of the back-up ring 13 is moved with a minimum clearance to an
internal wall 2 of the tube-shaped hollow body 1.

[0036] FIG. 3 shows in schematic illustration an arrangement of two
back-up rings 13 and 13' at the ends of a motor rotor 8. The illustration
of the tube-shaped hollow body 1 has been left out here.

[0037] FIG. 4 shows a further embodiment, according to the invention, of
the back-up ring 13. The internal surface 16 of the back-up ring 13 shows
a profile 15. As can be seen in the sectional illustration of the back-up
ring 13, the profile 15 is executed here in a bearing-surface similar
form. In this case also, the illustration of the tube-shaped hollow body
has been waived.

[0038] In a further embodiment of the invention, as shown in FIG. 5, a
back-up ring 13 is arranged without an illustration of the tube-shaped
hollow body 1, and this back-up ring covers the entire axial length of
the motor rotor 8 with its blading 11. The conveying of the fluid is also
effected here between the internal surface 16 of the back-up ring 13 and
the motor rotor 8.

[0039] In a further embodiment of the invention, a back-up ring is shown
in FIG. 6 whose running surface 14 has a raised running line 17 which
facilitates a minimum clearance combined with a minimum friction opposite
the internal wall 2 of the tube-shaped hollow body 1.